Cutting tools have long been known for use in cutting various types of cable. Common of all such cutting tools is the use of a pair of opposed movably supported cutting blades which accommodate the cable therebetween. Movement of the cutting blades towards one another effects slicing or cutting of the cable. Tools of this type, especially hand-held tools, take basically two configurations. The first is a simple scissor-type cutting tool where a pair of blades are mounted on adjacent ends of pivotally connected handles. The blades have opposed cutting surfaces between which the cable is positioned. Movement of the handles toward one another effects cutting action of the blades.
It is well known that this type of cutting tool may employ blades having straight cutting surfaces. In this manner, cutting engagement with a circular cable is ideally maintained at two opposed tangential points. Initially, this reduces the manual force needed to effect passage of the blades through the cable to effect cutting. However, this results in the need to apply an increased force as the cut nears completion. Also, this may result in damage or swaging of the cable ends during the cutting. This reduces the usefulness of the cable, or requires significant redressing of the cable ends prior to use.
Improved cutting tools such as the type shown in U.S. Pat. Nos. 2,794,250 and 4,229,881 attempt to solve the cable end problem by making curved cutting blades which at least partially circumscribe the cable during cutting. As shown particularly in the drawings of the '250 patent, the blades engage the cables nearly circumferentially. This enables the blades to cut through the cable without forcing the cable into an elliptical shape. While the '250 patent does describe limiting the arc-length engagement of the cutting blades with the cable during engagement, the actual engagement more closely approximates circumferential cutting than would be achieved with straight blades. While initially the curved blades of the '250 patent help maintain the cutting end in a circular configuration, it still requires increased manual effort to effect cutting.
Another type of hand-actuated cable cutting tool is the type where a pair of cutting blades are circumferentially movably connected at a hinge. Examples of such tools are shown in U.S. Pat. Nos. 4,223,439 and 5,184,404. A pair of movably connected handles are movable toward and away from one another to effect relative movement of the cutting blades under operation of a ratchet and pawl mechanism. The blades so supported define a bounded opening which surrounds the cable. This engagement assists in maintaining the cable in a circular configuration during cutting. In order to address the need for increased mechanical advantage to effect such circumferential cutting, these patents provide a ratchet mechanism to achieve a mechanical advantage. Continuous actuation of the handles causes the blade members to progressively close thereby severing the cable supported within the opening. Such tools, especially the tool shown in the '439 patent, are effective in cutting a cable and leaving a round end that needs little cable redressing.
The gradual curve of the blades of the '439 patent, especially near the end of the cutting cycle, effects an almond-like configuration for supporting the center or core of the cable for cutting. Referring to FIG. 1, the almond-like configuration provides for the cutting through of the center 1 of a cable at diametrically opposed locations, x--x spaced from the pivot point p of the blades 2 and 3. The cutting action is inward towards the center of the cable in a generally horizontal direction A--A. Near the end of the cutting cycle, while lesser force would ordinarily need be applied to cut the center portion or strand of the cable, a significant degree of manual effort is still required to cut the cable center due to the location and direction of cutting forces. Since a portion 4 of almond-like opening supporting center 1 of the cable is very narrow adjacent pivot p and tapers outwardly away therefrom, the tendency is to keep the center 1 of the cable away from the pivot p immediately thereadjacent.
While the tool of the '881 patent attempts to move the cable closer to the pivot, the particular shape of the blades shown therein fails to take full advantage of this feature. At a location nearest the pivot the blades define a similar almond-like configuration which fails to utilize the full mechanical advantage available.
Cables commonly used in the electrical industry for electrical conductivity are typically formed of copper and/or aluminum and may be of the type which are solid or stranded. While the tools described in both the '439 and '881 patents, with application of appropriate manual force, serve adequately to cut such copper or aluminum cables, it has been found that the particular configuration of the blades of these cutting tools make it difficult to cut cables formed of materials harder than copper or aluminum, say, for instance, steel. In many instances, tools such as these are sold in the commercial setting with an admonition against cutting steel cables. This is due, in part, because cutting blades specifically configured for cutting copper or aluminum are inappropriate and ineffective in cutting harder steel cable. Similarly, other blade configurations in other tools specifically designed for cutting steel would crush or otherwise damage copper or aluminum cables beyond the point at which the cut ends are useful.
The electrical industry has also seen the increasing use of a specialized cable known as aluminum cable steel-reinforced (ACSR). This type of cable includes one or more center reinforcing steel strands which are surrounded by outer strands of softer metal, such as aluminum. The cable cutting tools described above are inadequate in addressing the need to cut ACSR cable. As the almond-shaped configuration of the blade opening provided thereby holds the center strand 1 of the cable away from the pivot point p as shown in FIG. 1. The tool cannot effectively cut through the center strand due to blade damage and greater required force.
It is therefore desirable to provide a tool having an improved blade configuration. The improved tool would reduce the necessary force by keeping the cutting action close to the fulcrum, spread the required force over an extended distance to equalize and minimize force values, concentrate power where needed and reduce cable distortion. Such configuration would permit the easy and reliable cutting of many types and configurations of cable, including ACSR.